TTL Simulator In JavaScript

November 2, 2020 by 13 Comments

How do you celebrate your YouTube channel passing the 7400 subscriber mark? If you are [Low Level JavaScript], the answer is obvious: You create a 7400 TTL logic simulator in JavaScript. The gate simulations progress from simple gates up to flipflops and registers. You could probably build a 7400-based computer virtually with this code.

In addition to just being fun and interesting, there were a lot of links of interest in the video (see below) and its comments. For one, someone watching the channel took the code and made a Verilog-like IDE that is impressive.

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Building A Top-Notch Electret Microphone

November 2, 2020 by 25 Comments

Electret microphones are capable of high-quality output, and are prized for their smooth frequency response. However, unlike other types, they can’t simply be plugged directly into a mixing desk. Instead, they require special high-impedence circuitry to extract the audio signal for recording. [DJJules] is a big fan of these microphones, and decided to build a high-quality, easy to use circuit that he has shared with the community. 

The goal of the project was to create a circuit to match the TSB2555B electret capsule that could be used with phantom power, and that could be built with easily obtainable parts. [DJJules] had used FETs in the past, but grew tired of routinely having to hunt for obsolete parts. Instead, this design relies on a dual OPA1642 op-amp, with its low quiescent current meaning it’s perfect for running off phantom power. This means the microphone needs no batteries, and using a dual op-amp enables the circuit to properly drive a balanced audio connection.

The circuit is designed to fit inside a common BM700 or BM800 microphone body, and the PCB can be ordered from PCBWay for those interested in building their own. There’s also a saddle on Shapeways that’s designed to neatly mount the electret capsule within the housing.

The final results are impressive, and this project would make a great entry into the DIY microphone space for anyone eager to start building their own gear. Of course, there are simpler builds if you’re looking for an easier way to get started. Video after the break.

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Peter Sripol’s DIY Electric Ultralight MK4

November 2, 2020 by 70 Comments

Peter Sripol really likes building gravity defying death traps. He recently flew the fourth ultralight, which he designed and built himself. For a taste of what’s going on here, the wings have aluminum tube spars and are made of hot-wire-cut styrofoam sections.

To keep the plane simple, he got rid of ailerons entirely. For roll stabilization he angled up the wings noticeably, adding dihedral. This gives the aircraft passive stability, because as it rolls to a side, the upper wing’s lift decreases and the lower wing’s lift increases, forcing the plane to correct itself. Interestingly he kept the rudder controls on pedals instead of moving it to the stick, so the stick only controls the elevator.

It is powered by a single large brushless electric motor borrowed from the OpenPPG project. On the first test he used a two-bladed propeller, with a small pitch angle which required full throttle to keep flying. It can be compared to driving a car only in first gear. By moving to a three bladed propeller with a higher pitch angle, and increasing the length of the wings for more lift, [Peter] was able to cruise comfortably at about 30 MPH or 48 km/h.

Although this aircraft definitely performed better than [Peter]’s previous ultralight builds, piloting something like this isn’t for the faint of heart. Although he does extensive weight-loading and thrust testing before taking to the air, adding tail weight to piloted aircraft by simply taping a water bottle to the tail just felt wrong. But we aren’t aviation experts, so we won’t pass final judgement.

Robot Sink Helps With The Dishes

November 2, 2020 by 16 Comments

The humble kitchen sink has remained relatively unchanged over the last century. While there are now fancier mixing taps and sleeker fittings available, for most of us, there’s a nozzle that squirts water of varying temperature, and a tub in which to soak dishes. Of course, this leaves plenty of room for improvement, as [Jake] found with his robot sink build.

The sink consists of a robotic nozzle, which he refers to as a “continuum manipulator”. In essence, it’s a nozzle that can be steered with a joystick to aim the flow of water throughout the sink. To move the nozzle, motors pull on steel cables attached to 3D printed collars fastened around the hose. Combined with an on/off switch for the water flow, the sink could be a useful assistive technology for those with disabilities, as demonstrated in the project’s demo video.

We could easily imagine such hardware being combined with a simple computer vision system to further automate the cleaning of dishes. The project actually serves as a proof of concept for work [Jake] is doing to explore 3D printing concrete with similar hardware, albeit scaled up to a more industrial level. We’ve featured similar technology before, too — in the form of a DIY tentacle build that’s perfect for Halloween. Video after the break.

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OpenOffice Or LibreOffice? A Star Is Torn

November 2, 2020 by 105 Comments

When it comes to open source office suites, most people choose OpenOffice or LibreOffice, and they both look suspiciously similar. That isn’t surprising since they both started with exactly the same code base. However, the LibreOffice team recently penned an open letter to the Apache project — the current keepers of OpenOffice — asking them to redirect new users to the LibreOffice project. Their logic is that OpenOffice has huge name recognition, but hasn’t had a new major release in several years. LibreOffice, on the other hand, is a very active project. We could argue that case either way, but we won’t. But it did get us thinking about how things got here.

It all started when German Marco Börries wrote StarWriter in 1985 for the Zilog Z80. By 1986, he created a company, Star Division, porting the word processor to platforms like CP/M and MSDOS. Eventually, the company added other office suite programs and with support for DOS, OS/2, and Windows, the suite became known as StarOffice.

The program was far less expensive than most competitors, costing about $70, yet in 1999 that price point prompted Sun Microsystems to buy StarOffice. We don’t mean they bought a copy or a license, they bought the entire thing for just under $74 million. The story was that it was still cheaper than buying a license for each Sun employee, particularly since most had both a Windows machine and a Unix machine which still required some capability.

Sun in Charge

Sun provided StarOffice 5.2 in 2000 as a free download for personal use, which gave the software a lot of attention. It eventually released much of the code under an open source license producing OpenOffice. Sun contributed to the project and would periodically snapshot the code to market future versions of StarOffice.

This was the state of affairs for a while. StarOffice 6.0 corresponded to OpenOffice 1.0. In 2003, release 1.1 turned into StarOffice 7. A couple of years later, StarOffice 8/OpenOffice 2.0 appeared and by 2008, we had StarOffice 9 with OpenOffice 3.0 just before Oracle entered the picture.

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How Many Punches Does It Take?

November 2, 2020 by 3 Comments

Do you ever wonder just how many punches you have thrown? The answer is going to be different if you happen to use a punching bag as part of your exercise routine. So is the case with the [DuctTapeMechanic] and while restoring an old speed ball punching bag, he decided to combine his passions for sports and electronics by adding a punch counter.

Perhaps most interesting in this build is the method used to monitor the bag. A capacitance proximity sensor most often used for industrial automation is mounted in the wooden base. He just calls it “an NPN capacitive sensor” without mentioning part number but these are rather easy to find from the usual places. It has no problem sensing each punch — assuming you swing strong enough so that the bag comes near the sensor. Two battery packs, an Arduino, and an optocoupler round out the bill of materials. We were a little disappointed not to see any duct tape in the construction of this project, but since the electronics are outside and exposed to the elements, maybe duct tape will be used to install a roof in a future episode.

The [DuctTapeMechanic] likes to repurpose items which would otherwise be thrown away, which is something to be applauded. The frame of this punching bag was welded from a discarded metal bed frame (a regular occupant of crawl spaces and self storage places), and you might remember he repurposed the electric motor from a discarded clothes dryer last month, changing it into a disk sander.

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ESP32 Adds New Features To 1990s Home Alarm System

November 2, 2020 by 16 Comments

Given how fast technology is progressing, some consumer gadgets lend themselves to being replaced every few years. Mobile phones are a particularly good example of a device that you probably won’t want to hold onto for more than 4 years or so, with TVs not far behind them. On the other hand, something like a home alarm system can stay in the fight for decades. As long as it still goes off when somebody tries to pop a window, what more do you need?

Well if you’re like [Brett Laniosh], you might want the ability to arm the system and check its current status from your phone. But instead of getting a whole new system, he decided to upgrade his circa 1993 Gardiner Gardtec 800 alarm with an ESP32. As it so happens, the original panel has an expansion connector which he was able to tap into without making any modifications to the alarm itself. If you’ve got a similar panel, you might even be able to use his source code and circuit schematics to perform your own modification.

Optocouplers link the ESP and alarm panel.

Now we know what you’re thinking. Surely there’s a risk involved when trusting an ESP32 connected to the Internet with the ability to disarm your home alarm system. [Brett] has considered this, and made sure that the web server running on the microcontroller can only be accessed from the local network. If he does want to connect from beyond WiFi range, he does so through a VPN. In other words, his code is never directly exposed to the wilds of the Internet and is always hiding behind some kind of encryption.

The WiFi connection allows [Brett] to arm and disarm the alarm system remotely, check if it’s been triggered, and reset it if necessary, all from his smartphone. But he’s also added in a 433 MHz receiver so he can use simple handheld fobs to arm the system if he doesn’t want to go through the phone. Even if you dropped out the Internet connectivity, this alone is a pretty nice upgrade.

For those not afraid to take the more invasive route, you could potentially reverse engineer and reprogram your old alarm panel. Or you could even so the full DIY route and create your own low-cost alarm system using the ESP32 and off-the-shelf modules.